Ever wondered why opening loot boxes in video games had these elaborate over the top animations with lots of bright colors and effects?  It's for the same reason.  It's designed to trigger dopamine release in the brain.  Keeps ya hooked 

 Good book on how to engineer social media addiction

https://m.media-amazon.com/images/I/719fyFgdNJL._AC_UF1000,1000_QL80_.jpg